Quantum channel coding search method, device and electronic equipment

Abstract

The present disclosure provides a quantum channel coding search method, device and electronic device, which relate to the field of quantum computing technology, and specifically to the field of quantum communication technology. The specific implementation scheme is: obtaining the first structural information of the first quantum channel, the second structural information and target parameters of the parameterized quantum circuit, and the first quantum state; applying the unitary transformation of the parameterized quantum circuit to the first quantum state to obtain the second quantum state; based on the first structural information and the second quantum state, determining the value of the loss function of the parameterized quantum circuit, the loss function is inversely proportional to the quantum channel coherent information of the first quantum channel under the coding scheme corresponding to the second quantum state; based on the value of the loss function, iteratively updating the target parameters of the parameterized quantum circuit; outputting the first target coding scheme of the first quantum channel, characterizing the quantum state of the first target coding scheme as the quantum state obtained by applying the unitary transformation of the parameterized quantum circuit under the target parameters to the first quantum state.

Description

Technical Field

[0001] The present disclosure relates to the field of quantum computing technology, in particular to the field of quantum communication technology, and specifically to a quantum channel coding search method, device and electronic equipment. Background Art

[0002] With the development of quantum information science, quantum communication is a highly anticipated field in the information age. It can utilize the characteristics of quantum mechanics to achieve more efficient, secure and flexible communication methods. The core of quantum communication is to perform specific operations and transmissions on quantum bits that carry information through quantum channels. Quantum channels are media or channels used to transmit quantum information. They can be any physical system or device that allows quantum information transmission, such as optical fibers, free space, etc. However, these channels may be affected by interference and noise during information transmission. Therefore, quantum channel coding technology is crucial to the reliability and security of information transmission.

[0003] In actual situations, if you want to make full use of the advantages of a given quantum channel, you need to find a specific quantum channel coding scheme that is suitable for the quantum channel. However, it is difficult to find a high-quality quantum coding scheme. At present, you can find a relatively good quantum channel coding scheme among the known quantum channel coding schemes, but the search space is small and the communication efficiency of the quantum coding obtained by the search is relatively poor. Summary of the invention

[0004] The present disclosure provides a quantum channel coding search method, device and electronic device.

[0005] According to a first aspect of the present disclosure, a quantum channel coding search method is provided, comprising:

[0006] Acquire target information, the target information comprising: first structural information of a first quantum channel, second structural information and target parameters of a parameterized quantum circuit, and a first quantum state characterizing a coding scheme of the first quantum channel;

[0007] Applying a unitary transformation of the parameterized quantum circuit to the first quantum state to obtain a second quantum state representing the coding scheme of the first quantum channel; the unitary transformation is constructed based on the second structural information and target parameters;

[0008] Based on the first structural information and the second quantum state, determining a value of a loss function of the parameterized quantum circuit, wherein the loss function is inversely proportional to quantum channel coherence information of the first quantum channel under a coding scheme corresponding to the second quantum state;

[0009] Iteratively updating target parameters of the parameterized quantum circuit based on the value of the loss function;

[0010] When the iterative update of the target parameters is completed, a first target coding scheme of the first quantum channel is determined, and a quantum state representing the first target coding scheme is a quantum state obtained by applying a unitary transformation of a parameterized quantum circuit under the target parameters to the first quantum state.

[0011] According to a second aspect of the present disclosure, a quantum channel coding search device is provided, comprising:

[0012] An acquisition module, configured to acquire target information, wherein the target information includes: first structural information of a first quantum channel, second structural information and target parameters of a parameterized quantum circuit, and a first quantum state characterizing a coding scheme of the first quantum channel;

[0013] a transformation module, configured to perform a unitary transformation of the parameterized quantum circuit on the first quantum state to obtain a second quantum state representing the coding scheme of the first quantum channel; the unitary transformation is constructed based on the second structural information and a target parameter;

[0014] A first determining module is used to determine a value of a loss function of the parameterized quantum circuit based on the first structural information and the second quantum state, wherein the loss function is inversely proportional to quantum channel coherence information of the first quantum channel under a coding scheme corresponding to the second quantum state;

[0015] An iterative updating module, configured to iteratively update target parameters of the parameterized quantum circuit based on the value of the loss function;

[0016] The second determination module is used to determine a first target coding scheme for the first quantum channel when the iterative update of the target parameter is completed, and the quantum state representing the first target coding scheme is a quantum state obtained by applying a unitary transformation of a parameterized quantum circuit under the target parameter to the first quantum state.

[0017] According to a third aspect of the present disclosure, there is provided an electronic device, including:

[0018] at least one processor; and

[0019] a memory communicatively connected to at least one processor; wherein,

[0020] The memory stores instructions that can be executed by at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform any method in the first aspect.

[0021] According to a fourth aspect of the present disclosure, a non-transitory computer-readable storage medium storing computer instructions is provided, wherein the computer instructions are used to cause a computer to execute any one of the methods in the first aspect.

[0022] According to a fifth aspect of the present disclosure, a computer program product is provided, comprising a computer program, which implements any one of the methods in the first aspect when executed by a processor.

[0023] The technology disclosed in the present invention solves the problem in the related art that the search space for a relatively better quantum channel coding scheme among known quantum channel coding schemes is small, resulting in poor communication efficiency of the searched quantum coding, and can improve the information transmission efficiency of the quantum channel.

[0024] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to better understand the present solution and do not constitute a limitation of the present disclosure.

[0026] Figure 1 is a flow chart of a quantum channel coding search method according to the first embodiment of the present disclosure;

[0027] Figure 2 This is a schematic diagram of the architecture of the quantum information encoding search process;

[0028] Figure 3 is a schematic diagram of a first circuit structure;

[0029] Figure 4 is a schematic diagram of a second circuit structure;

[0030] Figure 5 is a schematic diagram of a third circuit structure;

[0031] Figure 6 is a schematic diagram of a fourth circuit structure;

[0032] Figure 7 is a schematic diagram of a fifth circuit structure;

[0033] Figure 8 is a schematic structural diagram of a quantum channel coding search device according to a second embodiment of the present disclosure;

[0034] Fig. 9 is a schematic block diagram of an example electronic device for implementing an embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] The following is a description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0036] First embodiment

[0037] like Figure 1 As shown, the present disclosure provides a quantum channel coding search method, comprising the following steps:

[0038] Step S101: acquiring target information, the target information comprising: first structural information of a first quantum channel, second structural information and target parameters of a parameterized quantum circuit, and a first quantum state characterizing a coding scheme of the first quantum channel;

[0039] In this embodiment, the quantum channel coding search method relates to the field of quantum computing technology, and in particular to the field of quantum communication technology, which can be widely used in quantum communication scenarios such as quantum secure communication and quantum communication network construction. The quantum channel coding search method of the disclosed embodiment can be performed by the quantum channel coding search device of the disclosed embodiment. The quantum channel coding search device of the disclosed embodiment can be configured in any electronic device to perform the quantum channel coding search method of the disclosed embodiment.

[0040] Quantum channel coding is the foundation of quantum communication theory and involves how to reliably transmit quantum information through noisy quantum channels. Just as classical channel coding in classical information theory is crucial to ensuring reliable communication, quantum channel coding plays a similar role in the field of quantum communication.

[0041] First, in actual quantum communication, information is often easily affected by environmental noise or other interference factors, which may lead to errors in information transmission. At this time, quantum channel coding introduces redundant information through a specific coding method, so that these errors can be detected and corrected to ensure the accuracy of the information.

[0042] Secondly, from the perspective of communication efficiency, the optimized coding method can enable more information to be efficiently transmitted in limited communication resources, thus improving the overall communication efficiency. In addition, quantum channel coding utilizes unique quantum properties such as quantum entanglement to ensure the confidentiality of information and effectively prevent unauthorized access and potential information leakage risks.

[0043] In actual situations, if we want to make full use of the advantages of a given quantum channel, we need to find a specific quantum channel coding scheme suitable for the quantum channel. In particular, for a quantum channel N from quantum system A′ to quantum system B A′→B , if φ AA′ is a quantum channel coding scheme, then Then naturally the channel is used twice Quantum channel coding scheme.

[0044] In order to make full use of the characteristics of quantum entanglement and improve the information transmission efficiency and reliability of quantum channels, we can consider quantum channel coherent coding (Quantum Coherent Code), that is, there is entanglement between the coded states of the quantum channel, which corresponds to finding an entangled quantum state ψ AAA′A′ The transmission efficiency is higher than However, for quantum channels that generally do not have special structures, it is very difficult to find a high-quality quantum channel coherent coding scheme.

[0045] However, high-quality quantum channel coding is of vital importance to quantum communication. First, high-quality quantum channel coding takes advantage of the characteristics of quantum parallelism, allowing the processing of multiple quantum bits of information in one transmission, which can significantly improve the efficiency of information transmission, especially when processing large-scale data.

[0046] Secondly, some high-quality quantum channel coding schemes allow information to be transmitted over long distances, which helps build a global secure communication network and improves the coverage and efficiency of information transmission. Quantum channel coding provides a secure way of communication. By utilizing the special properties of quantum states, such as quantum superposition and quantum entanglement, any eavesdropper can be detected and the security of communication can be maintained, which is essential for protecting sensitive information and achieving secure communications. In addition, high-quality quantum channel coding is essential for resisting noise and providing error correction performance, which can help ensure a low error rate during information transmission, thereby improving the reliability and efficiency of transmission.

[0047] In specific product requirements and application scenarios, the use of high-quality quantum channel coding is particularly important. In particular, quantum channel coding plays a key role in building quantum communication networks. When building quantum communication networks, it is necessary to find suitable quantum channel coding to efficiently and stably transmit information over long distances while maintaining the integrity and security of the information. This is of great significance for building a global secure communication network, quantum satellite communications and other fields.

[0048] However, searching for high-quality quantum channel coding is a very difficult problem. Although there are already existing quantum channel coding schemes, these quantum channel coding schemes are usually only effective for quantum channels with special structures. For general quantum channels, it is necessary to search for quantum channel coding schemes with high communication efficiency among some unknown but possible quantum channel coding schemes.

[0049] At present, relatively better quantum channel coding schemes can be found in known quantum channel coding schemes, but the search space is small and the communication efficiency of the quantum coding obtained by the search is relatively poor. The quantum channel coding scheme of this embodiment is applicable to any quantum channel, and the coding scheme can be searched in an unknown search space. The probability of searching for excellent quantum channel coding is higher, and a coding scheme that makes the information transmission effect of the quantum channel good can be searched.

[0050] The first quantum channel may be a single-bit quantum channel or a quantum channel in which at least two single-bit quantum channels are connected in parallel for transmission, which is not specifically limited here.

[0051] The first structure information may include the channel type and channel parameters of the first quantum channel. For example, if the channel type of the first quantum channel is a Pauli channel and the first quantum channel is formed by connecting other quantum channels in parallel, the first structure information may also include the number of parallel connections.

[0052] The first structural information of the first quantum channel may be obtained by user input or may be preset, or, in an actual scenario, the first structural information of the first quantum channel may also be obtained from a quantum communication network.

[0053] A parameterized quantum circuit (PQC) is a quantum circuit composed of quantum gates containing parameters, and is one of the ways to perform quantum machine learning. The second structural information can indicate the structure of the parameterized quantum circuit. For example, the second structural information can include the circuit width, circuit depth, and basic circuit structure of the parameterized quantum circuit. For example, the basic circuit structure includes a layer of single-qubit rotation gates and a layer of fully entangled layers composed of CNOT gates. The circuit width can indicate the number of quantum bits of the parameterized quantum circuit, and the circuit depth can indicate the number of basic circuit structures. For example, the parameterized quantum circuit has two basic circuit structures composed of a layer of single-qubit rotation gates and a layer of fully entangled layers composed of CNOT gates.

[0054] The second structural information of the parameterized quantum circuit may be input by a user or obtained by preset, or may be obtained by constructing a parameterized quantum circuit according to the first structural information of the first quantum channel, which is not specifically limited here.

[0055] The target parameters can be the parameters of the quantum gate. Different target parameters will result in different characterizations of the parameterized quantum circuit. In the initial stage, the target parameters obtained are the initial parameters of the parameterized quantum circuit, which are input or preset by the user.

[0056] The first quantum state may represent an initial code of the first quantum channel, which may be input by a user, obtained by preset, or generated according to preset rules.

[0057] Step S102: applying a unitary transformation of the parameterized quantum circuit to the first quantum state to obtain a second quantum state representing the coding scheme of the first quantum channel; the unitary transformation is constructed based on the second structural information and target parameters.

[0058] The variational quantum algorithm is the quantum counterpart of a very useful machine learning method on a classical computer. It trains by applying a unitary transformation U(θ) of a parameterized quantum circuit to the input quantum state and iteratively optimizing the parameterized quantum circuit using an optimizer. Therefore, the parameterized quantum circuit can be called a quantum neural network.

[0059] This embodiment is inspired by the variational quantum algorithm and searches for quantum channel codes in the search space by simulating the parameterized quantum circuit in the variational quantum algorithm on a classical computer. Its mathematical model can be expressed by the following formula (1).

[0060] |ψ(θ)>=U(θ)|ψ0> (1)

[0061] Wherein, in the above formula (1), |ψ0> is a first quantum state characterizing the coding scheme of the first quantum channel, which is the initial coding of the first quantum channel, θ is a target parameter, which is a vector composed of all parameters contained in the parameterized quantum circuit, |ψ(θ)> is a second quantum state characterizing a coding scheme of the first quantum channel, U(θ) is a unitary transformation of the parameterized quantum circuit, which is a characterization representation of the parameterized quantum circuit, and is determined by the second structural information and the target parameter of the parameterized quantum circuit, specifically, by the parameterized quantum circuit function indicated by the second structural information and the target parameter.

[0062] θ is different, |ψ(θ)> is different. It can be seen that the coding schemes corresponding to the target parameters of the parameterized quantum circuit can constitute the search space of quantum channel coding. The purpose of this embodiment is to iteratively update the target parameters of the parameterized quantum circuit to search for a good coding scheme from the search space.

[0063] Step S103: Based on the first structural information and the second quantum state, determine the value of the loss function of the parameterized quantum circuit, wherein the loss function is inversely proportional to the quantum channel coherence information of the first quantum channel under the coding scheme corresponding to the second quantum state.

[0064] The quantum neural network can be trained by iterating θ, which is equivalent to solving the optimization problem shown in (2).

[0065]

[0066] Here, C(θ) is a loss function associated with |ψ(θ)>.

[0067] In order to reflect the transmission capacity of the quantum channel, this embodiment can use the quantum channel coherence information of the quantum channel under the coding scheme as the optimization purpose to construct the loss function of the quantum neural network, and its loss function is inversely proportional to the quantum channel coherence information of the first quantum channel under the coding scheme corresponding to the second quantum state, that is, the loss function decreases as the quantum channel coherence information of the first quantum channel under the coding scheme corresponding to the second quantum state increases. Among them, the quantum channel coherence information is related to the relevant information of the first quantum channel and its coding scheme, that is, it can be determined based on the first structural information and the second quantum state.

[0068] In an optional implementation, the loss function may be the inverse of the quantum channel coherence information of the first quantum channel under the coding scheme corresponding to the second quantum state. Optionally, the loss function is determined based on the negative value of the quantum channel coherence information of the first quantum channel under the coding scheme corresponding to the second quantum state. Compared with the classical neural network, the quantum neural network constructed in this way has a relatively low iteration difficulty, thereby improving the search efficiency of the quantum channel coding scheme.

[0069] Optionally, the loss function C(θ)=-2 k *L*I(N,ψ(θ)); wherein θ is the target parameter, L is the circuit depth of the parameterized quantum circuit, k is the number of quantum bits of the parameterized quantum circuit, and I(N,ψ(θ)) is the quantum channel coherence information of the first quantum channel N under the coding scheme corresponding to the second quantum state ψ(θ).

[0070] By adding quantum neural network scale-related coefficients, such as L and k, to the loss function, the barren plateau effect of the quantum neural network can be alleviated and the gradient of the loss function can be amplified, thereby improving the iterative efficiency of the quantum neural network and further improving the search efficiency of quantum channel coding.

[0071] By taking the quantum channel coherence information of the quantum channel under the coding scheme as the optimization purpose to construct the loss function of the quantum neural network, the searched quantum channel coding can have better anti-environmental interference ability and information transmission efficiency.

[0072] Among them, the quantum channel coherent information of the quantum channel under the coding scheme can be converted into quantum relative entropy to be determined, and of course it can also be determined based on other methods, which are not specifically limited here.

[0073] Optionally, the quantum channel coherent information of the first quantum channel under the coding scheme corresponding to the second quantum state is the quantum relative entropy of a third quantum state and a fourth quantum state, the third quantum state is obtained based on the tensor product operation of the identity mapping of the input state of the first quantum channel on the first quantum system and the target output state, the fourth quantum state is obtained by mapping the target output state on the first quantum system to the unit matrix, the target output state is the output state of the first quantum channel under the coding scheme corresponding to the second quantum state, the input state of the first quantum channel includes the first quantum system and the second quantum system, and the first quantum channel is a quantum channel on the second quantum system.

[0074] According to the definition of quantum channel coding, for the quantum state ρ on the quantum system A, its von Neumann entropy can be defined as the following equation (3).

[0075] H(A) ρ ≡-Tr{ρ A logρ A} (3)

[0076] For a quantum state ρ represented by a density matrix operator and another semi-positive definite operator σ, the definition of quantum relative entropy is expressed as follows (4).

[0077]

[0078] In the above formula (4), Tr represents the trace of the matrix, and supp represents the linear space composed of the eigenvectors corresponding to the non-zero eigenvalues ​​of the matrix.

[0079] Quantum system A and quantum system B, for The quantum state ρ on AB , and its quantum channel coherence information is defined as shown in the following formula (5).

[0080] I(A>B) ρ ≡H(B) ρ -H(AB) ρ (5)

[0081] The quantum channel coherence information defined in the above formula (5) can be converted into quantum relative entropy for calculation, as shown in the following formula (5).

[0082]

[0083] Among them, I A is the identity matrix of quantum system A, and is defined as:

[0084]

[0085] In the above formula (7), A′ has the same dimension as A, ψ AA' is a pure state and corresponds to a code of the quantum channel, N A'→B (ψ AA' ) is the output state of the quantum channel, and I(N,ψ) measures the quantum channel coding ψ for quantum channel N. AA' The larger the value, the better the information transmission effect. For the quantum channel N from quantum system A′ to quantum system B, A'→B , the definition of quantum channel coherence information is as shown in the following equation (8).

[0086]

[0087] Among them, ψ AA' for In the definition, the quantum state ψ that makes the right side of equation (8) reach the maximum value AA' That is the optimal quantum channel code for quantum channel N. However, it is not easy to accurately calculate the optimal value on the right side of the equation. Therefore, it is hoped to find a quantum state that makes the right side of the equation as large as possible as a high-quality quantum channel code for the quantum channel.

[0088] In this step, the quantum channel coherent information of the first quantum channel under the coding scheme corresponding to the second quantum state can be determined according to the above equations (3)-(8) and the quantum relative entropy, which can be expressed by the following equation (9).

[0089]

[0090] Among them, I A is the identity mapping of the input state of the first quantum channel on quantum system A, i.e., the first quantum system, R I is the mapping of the input state of the first quantum channel from the quantum state in quantum system A to the unit matrix, N A'→B (ψ AA' (θ)) is the output state of the first quantum channel under the encoding scheme corresponding to the second quantum state, and quantum system A' is the second quantum system.

[0091] In an optional implementation, the loss function can be calculated using the following formula (10).

[0092]

[0093] In this way, the calculation of coherent information of the quantum channel can be realized, and then the loss function of the quantum neural network can be easily constructed to realize the iterative update of the parameters of the quantum neural network.

[0094] Step S104: iteratively updating target parameters of the parameterized quantum circuit based on the value of the loss function.

[0095] Based on the value of the loss function, the target parameters of the parameterized quantum circuit can be iteratively updated using a gradient-dependent optimization method, or the target parameters of the parameterized quantum circuit can be iteratively updated using a non-gradient-dependent optimization method, which is not specifically limited here.

[0096] In an optional implementation, the loss function of the above formula (10) is a highly nonlinear function, which has many local minima. If a gradient-dependent optimization method is used, such as a stochastic gradient descent optimizer or an Adam optimizer, the training effect of the quantum neural network is likely to be poor and limited to a local minimum. Optionally, the step S104 specifically includes:

[0097] Based on the value of the loss function, the target parameters of the parameterized quantum circuit are iteratively updated using a non-gradient dependent optimization method.

[0098] That is, a non-gradient dependent optimizer may be used. In some implementations, a genetic algorithm and a pattern search may be selected to iteratively update the target parameters of the parameterized quantum circuit based on the value of the loss function.

[0099] In this way, the training effect of the quantum neural network can be improved, thereby improving the search effect of quantum channel coding, so as to search for a better quantum channel coding.

[0100] Step S105: when the iterative update of the target parameters is completed, determining a first target coding scheme for the first quantum channel, wherein a quantum state representing the first target coding scheme is a quantum state obtained by applying a unitary transformation of a parameterized quantum circuit under the target parameters to the first quantum state.

[0101] When the optimizer determines that the conditions for stopping iteration are met, it means that the iterative update of the target parameters is completed. When the loss function converges or reaches the accuracy requirement, the optimizer can determine that the conditions for stopping iteration are met.

[0102] When the target parameter is updated iteratively, its target parameter is θ in the above formula (2): * , and |ψ(θ * )> is a quantum state of a first target coding scheme characterizing a first quantum channel.

[0103] Figure 2 This is a schematic diagram of the architecture of the quantum information encoding search process, such as Figure 2 As shown in FIG. 1 , the quantum channel coding search process requires three components, namely, parameterized quantum circuit, loss function and optimizer. The known initial quantum channel code can be input, and after the parameterized quantum circuit is applied to it, a new quantum channel code can be output. The loss function is constructed based on the quantum channel coherence information of the first quantum channel under the new quantum channel code. The loss function is then input into the optimizer to iteratively update the target parameters of the parameterized quantum circuit based on the value of the loss function. The quantum channel code output by the parameterized quantum circuit is also iteratively updated accordingly. After the iterative error reaches the accuracy requirement, the first target coding scheme |ψ(θ * )>.

[0104] The specific process of using parameterized quantum circuits to search for quantum channel coding is as follows:

[0105] Input: the first quantum channel N, the initial quantum channel code |ψ0>, the second structural information of the parameterized quantum circuit, the initial parameter θ0 of the parameterized quantum circuit;

[0106] Output: The searched quantum channel code |ψ(θ * )>.

[0107] Step 1: Using the second structural information and parameters of the input parameterized quantum circuit, construct the unitary transformation U(θ) of the parameterized quantum circuit;

[0108] Step 2: Substitute the parameter value θ of the parameterized quantum circuit i , and the parameterized quantum circuit acts on the initial quantum channel code |ψ0>, and the quantum channel code |ψ(θ i )>;

[0109] Step 3: Based on the obtained quantum channel coding, a loss function is constructed using the above formula (10), and the value of the loss function is calculated;

[0110] Step 4: Use the given optimizer to iteratively update the parameters of the parameterized quantum circuit to obtain θ i+1 ;

[0111] Step 5: Loop through steps 2 to 4. When the optimizer determines that the conditions for stopping iteration are met, it outputs |ψ(θ *)> as high-quality quantum channel coding.

[0112] In this way, the construction method of quantum channel coding is relatively intuitive, and quantum channel coding can be searched in an unknown search space. It is applicable to any quantum channel, and the communication efficiency of the searched quantum code can be relatively high, which can improve the information transmission efficiency of the quantum channel and the search efficiency of the quantum channel coding scheme.

[0113] Furthermore, the parameterized quantum circuit optimization in this embodiment requires relatively few parameters, and the probability of searching for a better quantum channel code is high. Adjusting the parameters has little effect on the output of the result, thereby making the optimization result more stable and improving the robustness of the algorithm.

[0114] Optionally, the second structural information of the parameterized quantum circuit is obtained in the following manner:

[0115] Based on the first structural information of the first quantum channel, the parameterized quantum circuit is constructed to obtain the second structural information.

[0116] The parameterized quantum circuit can be constructed according to the structure of the quantum channel. In an optional implementation, based on the first structural information of the first quantum channel, a rotation gate and an entanglement gate can be selected, and the parameterized quantum circuit can be modeled and constructed to obtain its second structural information.

[0117] In another optional implementation, regardless of whether the quantum channel has a specific structure, the existing basic structure settings of the parameterized circuit can be used to construct the parameterized quantum circuit to obtain the second structural information of the parameterized quantum circuit.

[0118] For example, according to the channel type of the first quantum channel, a circuit basic structure matching the channel type can be selected from the existing parameterized circuit basic structures. For another example, according to the number of parallel connections in the first structure information of the first quantum channel, the circuit depth and circuit width of the parameterized quantum circuit can be determined.

[0119] It should be noted that the structure of the parameterized quantum circuit is different, and the search space is also different when searching for the quantum channel coding scheme. In practical applications, the parameterized quantum circuit can be constructed in combination with the first structural information of the first quantum channel and the application scenario, so that the search space corresponding to the constructed parameterized quantum circuit can match the coding scheme of the first quantum channel and conform to the actual scenario.

[0120] The circuit structures of different parameterized quantum circuits correspond to a subspace in the full space of quantum channel coding, and usually, the circuit structures of parameterized quantum circuits are different, and the range and size of their search space are also different.

[0121] For example, in the scenario of quantum secure communication, the required quantum channel coding must not only ensure the efficiency of information transmission, but also have a certain ability to resist noise and provide error correction performance. When constructing parameterized quantum circuits, it is possible to search in the entire space of quantum channel coding to search for relatively high-quality quantum channel coding. Therefore, when constructing parameterized quantum circuits, a variety of basic circuit structures can be combined, and the search space of quantum channel coding can be increased by increasing the circuit width and circuit depth of the parameterized quantum circuit, so as to increase the probability of searching for high-quality quantum channel coding.

[0122] In this way, a parameterized quantum circuit can be constructed based on the structure of the first quantum channel. For quantum channels with special structures or special scenarios, the search range of quantum channel coding can be adjusted by combining the structure and application scenarios of the quantum channel and constructing a parameterized quantum circuit. The implementation method of quantum information coding search is more flexible, and the search results are more stable and have better robustness. It can be applied to more quantum channels, so that it can cope with a wider range of application scenarios in practical applications.

[0123] The circuit structure can be selected from the settings of the existing parameterized circuit basic structure to construct the parameterized quantum circuit. Optionally, the parameterized quantum circuit includes any of the following circuit structures:

[0124] A first circuit structure, wherein the first circuit structure comprises a layer of single-qubit rotation gates and a layer of fully entangled layers composed of CNOT gates according to the time evolution direction of the quantum state;

[0125] A second circuit structure, wherein the second circuit structure comprises, according to the time evolution direction of the quantum state, a layer of y-axis single-qubit rotation gate, a layer of linear entanglement layer composed of CNOT gates, a layer of z-axis single-qubit rotation gate and a layer of linear entanglement layer;

[0126] A third circuit structure, wherein the third circuit structure comprises a layer of y-axis single quantum bit rotation gate and a layer of full entanglement layer according to the time evolution direction of the quantum state;

[0127] A fourth circuit structure, wherein the fourth circuit structure includes three first blocks consisting of two quantum bits, wherein the first block includes a block consisting of four single-qubit rotation gates and a CNOT gate entangled between the four single-qubit rotation gates, and the first block in the later direction of the quantum state time evolution respectively shares a single-qubit rotation gate with the two first blocks in the front;

[0128] A fifth circuit structure, the fifth circuit structure includes three second blocks consisting of two quantum bits, the second blocks include a block consisting of four y-axis single-qubit rotation gates and a CNOT gate entangled between the four y-axis single-qubit rotation gates, and the second blocks at the rear in the direction of quantum state time evolution share a y-axis single-qubit rotation gate with the two preceding second blocks respectively.

[0129] The above five circuit structures are some examples of existing basic structures of parameterized circuits. When constructing parameterized quantum circuits, you can choose from the above five circuit structures. The circuit width and circuit depth can be determined based on parameters such as channel type and number of parallel connections.

[0130] For example, for a first quantum channel formed by connecting n single-bit Pauli channels in parallel, a first circuit structure can be selected as a basic structure of a parameterized quantum circuit, and the circuit depth of the parameterized quantum circuit is 2 and the circuit width is 2n.

[0131] Figure 3 is a schematic diagram of the first circuit structure, such as Figure 3 As shown, it consists of a single-qubit rotating gate 301 and a full entanglement layer 302, which can be called a complex-full entanglement setting. In the full entanglement layer, the qubit of qubit j and the qubit of qubit j+1 are entangled in sequence through CNOT gates in the order from small to large starting from j 0, and the last qubit is also entangled with the first qubit through CNOT gates.

[0132] Figure 4 is a schematic diagram of the second circuit structure, such as Figure 4 As shown, it is composed of a layer of y-axis single-qubit rotating gate 401, a layer of linear entanglement layer 402 composed of CNOT gates, a layer of z-axis single-qubit rotating gate 403 and a layer of linear entanglement layer 404, which can be called a linear entanglement setting. In the linear entanglement layer, entanglement is performed between the qubit of qubit j and the qubit of qubit j+1 in sequence from small to large starting from j 0 through CNOT gates.

[0133] Figure 5 is a schematic diagram of the third circuit structure, such as Figure 5 As shown, it consists of a layer of y-axis single quantum bit rotating gate 501 and a layer of full entanglement layer 502, which is called real-full entanglement setting.

[0134] Figure 6 is a schematic diagram of a fourth circuit structure, such as Figure 6 As shown, it is composed of a first block 601, a first block 602 and a first block 603, which is called a complex block setting. The first block 603 shares a single quantum bit rotating gate with the first block 601 and the first block 602 respectively. Figure 7 is a schematic diagram of a fifth circuit structure, such as Figure 7 As shown, it is composed of a second block 701, a second block 702 and a second block 703, which is called a real block setting. The second block 703 shares a y-axis single quantum bit rotation gate with the second block 701 and the second block 702 respectively.

[0135] By repeating the circuit setting L times, a parameterized quantum circuit with L layers can be obtained. In the above circuit structure, U3 is a single-qubit rotation gate, R y is the y-axis single-qubit rotation gate, R z It is a z-axis single-qubit rotation gate, and the entanglement between qubits is achieved by a CNOT gate.

[0136] In this way, the circuit structure can be selected from the settings of the existing basic structure of the parameterized circuit, simplifying the construction process of the parameterized quantum circuit.

[0137] Optionally, after step S105, the method further includes:

[0138] If the information transmission capacity of the first quantum channel under the first target coding scheme does not meet a preset condition, adjusting the structure of the parameterized quantum circuit;

[0139] Searching for a coding scheme for the first quantum channel in a search space corresponding to the parameterized quantum circuit after structural adjustment, so as to output a second target coding scheme that enables the information transmission capability of the first quantum channel to meet the preset condition;

[0140] Among them, if the quantum channel coherence information of the first quantum channel under the first target coding scheme is less than a preset threshold, and / or the information transmission efficiency of the first quantum channel under the first target coding scheme is less than or equal to the information transmission efficiency of the fourth quantum channel, it is determined that the information transmission capacity of the first quantum channel under the first target coding scheme does not meet the preset conditions, and the first quantum channel is formed by connecting the fourth quantum channels in parallel.

[0141] Due to the limitation of the parameterized quantum circuit structure, the search space of quantum channel coding is limited, and the first target coding scheme searched from the search space corresponding to the parameterized quantum circuit may not be a relatively optimal coding scheme. The superiority of the first target coding scheme can be determined by determining whether the information transmission capacity of the first quantum channel under the first target coding scheme meets the preset conditions.

[0142] If the information transmission capacity of the first quantum channel under the first target coding scheme does not meet the preset conditions, it means that the first target coding scheme does not meet the requirements of quantum communication. In this case, the structure of the parameterized quantum circuit can be adjusted to adjust the search space of quantum channel coding.

[0143] If the quantum channel coherence information of the first quantum channel under the first target coding scheme is less than a preset threshold, and / or the information transmission efficiency of the first quantum channel under the first target coding scheme is less than or equal to the information transmission efficiency of the fourth quantum channel, it is determined that the information transmission capacity of the first quantum channel under the first target coding scheme does not meet the preset conditions.

[0144] The preset threshold value can be set according to actual conditions and is not specifically limited here. The fourth quantum channel can be a single-bit quantum channel, such as a single-bit Pauli channel.

[0145] The information transmission efficiency of the first quantum channel under the first target coding scheme and the information transmission efficiency of the fourth quantum channel can be compared by the following formula (11). The channel transmission efficiency of the fourth quantum channel can refer to the information transmission efficiency of the fourth quantum channel under a better coding. The better coding scheme of the fourth quantum channel can also be obtained by searching by applying the quantum channel search method of this embodiment.

[0146]

[0147] It is hoped that quantum channel coding can maximize the information transmission capacity of quantum channels and resist the influence of environmental noise to the greatest extent. Therefore, quantum channels can usually use quantum channel coherent coding when transmitting information, that is, quantum channels are transmitted in parallel and encoded as a whole to improve information transmission capacity.

[0148] In the above formula (11), the larger Δ is, the stronger the anti-noise capability of the searched quantum channel coding is, and the higher the information transmission efficiency using the quantum channel coherent coding is, making the parallel transmission super-additive.

[0149] In the above formula (11), if N is the fourth quantum channel, is the first quantum channel, ψ is the first target coding scheme, when Δ>0, it can be said that the information transmission efficiency of the first quantum channel under the first target coding scheme is greater than the information transmission efficiency of the fourth quantum channel, and the first quantum channel has superadditivity. Otherwise, it means that the information transmission efficiency of the first quantum channel under the first target coding scheme is less than or equal to the information transmission efficiency of the fourth quantum channel.

[0150] If the information transmission capacity of the first quantum channel under the first target coding scheme does not meet the preset conditions, in an optional implementation, the scope of the search space can be adjusted by adjusting the construction method of the parameterized quantum circuit, for example, reselecting the basic circuit structure of the parameterized quantum circuit to adjust the search space of the quantum channel coding. In another optional implementation, the size of the search space can be controlled by adjusting scale parameters such as the circuit depth and width of the parameterized quantum circuit, for example, expanding the circuit width and depth of the parameterized quantum circuit to expand the size of the search space.

[0151] On the basis of adjusting the structure of the parameterized quantum circuit, the search space of the quantum channel coding is adjusted accordingly. The quantum channel coding search method of this embodiment can be applied to search for the coding scheme of the first quantum channel again in the new search space, so as to search for a second target coding scheme that makes the information transmission capacity of the first quantum channel meet the preset conditions, and output it, so as to apply the searched second target coding scheme to quantum communication.

[0152] In this way, the search efficiency of quantum channel coding can be further improved, and quantum channel coding with relatively high communication efficiency can be searched.

[0153] Optionally, the first quantum channel is a quantum channel in which n second quantum channels are transmitted in parallel, and the information transmission efficiency of the first quantum channel under the first target coding scheme is greater than the information transmission efficiency of the second quantum channel transmitted n times, where n is a positive integer greater than 1.

[0154] In this implementation, the second quantum channel may be a single-bit quantum channel, and the first quantum channel is a quantum channel in which at least two single-bit quantum channels are transmitted in parallel. Accordingly, the first target coding scheme is quantum channel coherent coding, and the quantum channel coherent coding searched out in this embodiment can improve the information transmission efficiency of the quantum channel.

[0155] The quality of the quantum channel codes searched by the quantum channel code search method of this embodiment can be judged through numerical experiments.

[0156] The parameterized quantum circuit is set to complex-full entanglement, the circuit depth is 2, the circuit width k=2n, and n is the number of parallel quantum channels. The parameters of the parameterized quantum circuit are updated using a non-gradient dependent optimizer, which selects a genetic algorithm. The settings of the genetic algorithm are: the population size is 300, the upper limit of the population iteration number is 150, and the other parameters are set by default.

[0157] Experiment 1: Comparing the commonly used repetition codes with the quantum channel coding searched in this embodiment. Taking a single-bit Pauli channel as an example, its specific mathematical form is shown in the following equation (12).

[0158] N(ρ)=(1-p1-p2-p3)ρ+p1XρX+p2YρY+p3ZρZ (12)

[0159] Among them, X, Y, Z are Pauli matrices. When the parameters are taken as p1 = 0.01, p2 = 0.03, p3 = 0.2, consider finding ψ such that As large as possible. The quantum channel coding expression searched by this embodiment is shown in the following formula (13).

[0160]

[0161] The corresponding value of quantum channel coherent information is Δ=0.0051>0; and the coherent information of the quantum channel under the repetition code is always negative, that is, Δ<0.

[0162] It can be seen that the quantum channel coding scheme at the search location in this embodiment is of higher quality.

[0163] Optionally, the number of the first quantum channels includes m, each first quantum channel is formed by connecting third quantum channels of the same type in parallel, different first quantum channels correspond to different third quantum channels, m is a positive integer greater than 1, and the method further includes:

[0164] Based on a first target coding scheme for each first quantum channel, a target quantum channel is selected from the m first quantum channels, and the information transmission efficiency of the target quantum channel under the first target coding scheme is greater than the information transmission efficiency of a third quantum channel corresponding to the target quantum channel transmitted k times, where k is the number of third quantum channels in parallel.

[0165] The third quantum channel may be a single-bit quantum channel, and the plurality of first quantum channels are all formed by connecting the third quantum channels of the same type in parallel. For example, the third quantum channel may be a single-bit Pauli channel, and a first quantum channel may be formed by connecting the plurality of third quantum channels of the same parameters in parallel. The parameters of the third quantum channels are different, and the first quantum channels they constitute are also different.

[0166] Based on the first target coding scheme of the first quantum channel, a first quantum channel with super additivity can be screened out, that is, a quantum channel coherent coding that improves information transmission efficiency exists.

[0167] Experiment 2: Still taking the single-bit Pauli channel as an example, the three parameters of the Pauli channel are traversed in the range of [0, 0.2] with a step size of 0.01. Take n = 2 and discuss the superadditivity of two single-bit Pauli channels, that is, find quantum channel codes that satisfy the following equation (14).

[0168]

[0169] Based on the coding scheme of each quantum channel searched, 68 single-bit Pauli channels with superadditivity were found from the above quantum channels. The corresponding parameter settings are shown in Table 1 below, which locks the approximate range of Pauli channels with superadditivity, so that the superadditivity of these quantum channels can be brought into play during quantum communication.

[0170] At the same time, we can also search for multiple quantum channel codes that can achieve superadditivity, for example, quantum channel coding Second embodiment

[0171] like Figure 8 As shown, the present disclosure provides a quantum channel coding search device 800, comprising:

[0172] An acquisition module 801 is used to acquire target information, wherein the target information includes: first structural information of a first quantum channel, second structural information and target parameters of a parameterized quantum circuit, and a first quantum state representing a coding scheme of the first quantum channel;

[0173] A transformation module 802 is used to apply a unitary transformation of the parameterized quantum circuit to the first quantum state to obtain a second quantum state representing the coding scheme of the first quantum channel; the unitary transformation is constructed based on the second structural information and target parameters;

[0174] A first determining module 803 is used to determine a value of a loss function of the parameterized quantum circuit based on the first structural information and the second quantum state, wherein the loss function is inversely proportional to quantum channel coherence information of the first quantum channel under a coding scheme corresponding to the second quantum state;

[0175] An iterative updating module 804, configured to iteratively update target parameters of the parameterized quantum circuit based on the value of the loss function;

[0176] The second determination module 805 is used to determine a first target coding scheme for the first quantum channel when the iterative update of the target parameter is completed, and the quantum state representing the first target coding scheme is a quantum state obtained by applying a unitary transformation of a parameterized quantum circuit under the target parameter to the first quantum state.

[0177] Optionally, the first quantum channel is a quantum channel in which n second quantum channels are transmitted in parallel, and the information transmission efficiency of the first quantum channel under the first target coding scheme is greater than the information transmission efficiency of the second quantum channel transmitted n times, where n is a positive integer greater than 1.

[0178] Optionally, the number of the first quantum channels includes m, each first quantum channel is formed by connecting third quantum channels of the same type in parallel, different first quantum channels correspond to different third quantum channels, m is a positive integer greater than 1, and the device further includes:

[0179] A screening module is used to screen out a target quantum channel from the m first quantum channels based on a first target coding scheme of each first quantum channel, wherein the information transmission efficiency of the target quantum channel under the first target coding scheme is greater than the information transmission efficiency of a third quantum channel corresponding to the target quantum channel transmitted k times, where k is the number of third quantum channels connected in parallel.

[0180] Optionally, the loss function is determined based on a negative value of quantum channel coherence information of the first quantum channel under a coding scheme corresponding to the second quantum state.

[0181] Optionally, the loss function C(θ)=-2 k *L*I(N,ψ(θ)); wherein θ is the target parameter, L is the circuit depth of the parameterized quantum circuit, k is the number of quantum bits of the parameterized quantum circuit, and I(N,ψ(θ)) is the quantum channel coherence information of the first quantum channel N under the coding scheme corresponding to the second quantum state ψ(θ).

[0182] Optionally, the quantum channel coherent information of the first quantum channel under the coding scheme corresponding to the second quantum state is the quantum relative entropy of a third quantum state and a fourth quantum state, the third quantum state is obtained based on the tensor product operation of the identity mapping of the input state of the first quantum channel on the first quantum system and the target output state, the fourth quantum state is obtained by mapping the target output state on the first quantum system to the unit matrix, the target output state is the output state of the first quantum channel under the coding scheme corresponding to the second quantum state, the input state of the first quantum channel includes the first quantum system and the second quantum system, and the first quantum channel is a quantum channel on the second quantum system.

[0183] Optionally, the second structural information of the parameterized quantum circuit is obtained in the following manner:

[0184] Based on the first structural information of the first quantum channel, the parameterized quantum circuit is constructed to obtain the second structural information.

[0185] Optionally, the device further comprises:

[0186] an adjustment module, configured to adjust the structure of the parameterized quantum circuit if the information transmission capability of the first quantum channel under the first target coding scheme does not meet a preset condition;

[0187] An output module, configured to search for a coding scheme of the first quantum channel in a search space corresponding to the parameterized quantum circuit after structural adjustment, so as to output a second target coding scheme that enables the information transmission capacity of the first quantum channel to meet the preset condition;

[0188] Among them, if the quantum channel coherence information of the first quantum channel under the first target coding scheme is less than a preset threshold, and / or the information transmission efficiency of the first quantum channel under the first target coding scheme is less than or equal to the information transmission efficiency of the fourth quantum channel, it is determined that the information transmission capacity of the first quantum channel under the first target coding scheme does not meet the preset conditions, and the first quantum channel is formed by connecting the fourth quantum channels in parallel.

[0189] Optionally, the parameterized quantum circuit includes any of the following circuit structures:

[0190] A first circuit structure, wherein the first circuit structure comprises a layer of single-qubit rotation gates and a layer of fully entangled layers composed of CNOT gates according to the time evolution direction of the quantum state;

[0191] A second circuit structure, wherein the second circuit structure comprises, according to the time evolution direction of the quantum state, a layer of y-axis single-qubit rotation gate, a layer of linear entanglement layer composed of CNOT gates, a layer of z-axis single-qubit rotation gate and a layer of linear entanglement layer;

[0192] A third circuit structure, wherein the third circuit structure comprises a layer of y-axis single quantum bit rotation gate and a layer of full entanglement layer according to the time evolution direction of the quantum state;

[0193] A fourth circuit structure, wherein the fourth circuit structure includes three first blocks consisting of two quantum bits, wherein the first block includes a block consisting of four single-qubit rotation gates and a CNOT gate entangled between the four single-qubit rotation gates, and the first block in the later direction of the quantum state time evolution respectively shares a single-qubit rotation gate with the two first blocks in the front;

[0194] A fifth circuit structure, the fifth circuit structure includes three second blocks consisting of two quantum bits, the second blocks include a block consisting of four y-axis single-qubit rotation gates and a CNOT gate entangled between the four y-axis single-qubit rotation gates, and the second blocks at the rear in the direction of quantum state time evolution share a y-axis single-qubit rotation gate with the two preceding second blocks respectively.

[0195] Optionally, the iterative update module 804 is specifically configured to:

[0196] Based on the value of the loss function, the target parameters of the parameterized quantum circuit are iteratively updated using a non-gradient dependent optimization method.

[0197] The quantum channel coding search device 800 provided in the present disclosure can implement each process implemented by the quantum channel coding search method embodiment and can achieve the same beneficial effects. To avoid repetition, it will not be described here.

[0198] In the technical solution of the present disclosure, the collection, storage, use, processing, transmission, provision and disclosure of user personal information involved are in compliance with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0199] According to an embodiment of the present disclosure, the present disclosure also provides an electronic device, a readable storage medium and a computer program product.

[0200] Fig. 9 A schematic block diagram of an example electronic device that can be used to implement an embodiment of the present disclosure is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present disclosure described and / or required herein.

[0201] like Fig. 9 As shown, the device 900 includes a computing unit 901, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 902 or a computer program loaded from a storage unit 908 into a random access memory (RAM) 903. In the RAM 903, various programs and data required for the operation of the device 900 can also be stored. The computing unit 901, the ROM 902, and the RAM 903 are connected to each other via a bus 904. An input / output (I / O) interface 905 is also connected to the bus 904.

[0202] A number of components in the device 900 are connected to the I / O interface 905, including: an input unit 906, such as a keyboard, a mouse, etc.; an output unit 907, such as various types of displays, speakers, etc.; a storage unit 908, such as a disk, an optical disk, etc.; and a communication unit 909, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 909 allows the device 900 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0203] The computing unit 901 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the computing unit 901 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The computing unit 901 performs the various methods and processes described above, such as the quantum channel coding search method. For example, in some embodiments, the quantum channel coding search method may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit 908. In some embodiments, part or all of the computer program may be loaded and / or installed on the device 900 via the ROM 902 and / or the communication unit 909. When the computer program is loaded into the RAM 903 and executed by the computing unit 901, one or more steps of the quantum channel coding search method described above may be performed. Alternatively, in other embodiments, the computing unit 901 may be configured to perform the quantum channel coding search method in any other appropriate manner (e.g., by means of firmware).

[0204] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0205] The program code for implementing the method of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0206] In the context of the present disclosure, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0207] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0208] The systems and techniques described herein may be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), and the Internet.

[0209] A computer system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The relationship of client and server is generated by computer programs running on respective computers and having a client-server relationship with each other. The server may be a cloud server, a server of a distributed system, or a server combined with a blockchain.

[0210] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0211] The above specific implementations do not constitute a limitation on the protection scope of the present disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A quantum channel coding search method, comprising: Acquire target information, the target information including: first structural information of a first quantum channel, second structural information and target parameters of a parameterized quantum circuit, and a first quantum state characterizing a coding scheme of the first quantum channel; the first structural information includes a channel type and a channel parameter of the first quantum channel, the second structural information is used to indicate a structure of the parameterized quantum circuit, and the target parameters are parameters of a quantum gate of the parameterized quantum circuit; Applying a unitary transformation of the parameterized quantum circuit to the first quantum state to obtain a second quantum state representing the coding scheme of the first quantum channel; the unitary transformation is constructed based on the second structural information and target parameters; Based on the first structural information and the second quantum state, determining a value of a loss function of the parameterized quantum circuit, wherein the loss function is inversely proportional to quantum channel coherence information of the first quantum channel under a coding scheme corresponding to the second quantum state; Iteratively updating target parameters of the parameterized quantum circuit based on the value of the loss function; When the iterative update of the target parameters is completed, a first target coding scheme of the first quantum channel is determined, and a quantum state representing the first target coding scheme is a quantum state obtained by applying a unitary transformation of a parameterized quantum circuit under the target parameters to the first quantum state.

2. The method according to claim 1, wherein: The first quantum channel is a quantum channel in which n second quantum channels are transmitted in parallel, and the information transmission efficiency of the first quantum channel under the first target coding scheme is greater than the information transmission efficiency of the second quantum channel transmitted n times, where n is a positive integer greater than 1.

3. The method according to claim 1, wherein: The number of the first quantum channels includes m, each first quantum channel is formed by connecting third quantum channels of the same type in parallel, different first quantum channels correspond to different third quantum channels, and m is a positive integer greater than 1. The method further includes: Based on a first target coding scheme for each first quantum channel, a target quantum channel is selected from the m first quantum channels, and the information transmission efficiency of the target quantum channel under the first target coding scheme is greater than the information transmission efficiency of a third quantum channel corresponding to the target quantum channel transmitted k times, where k is the number of third quantum channels in parallel.

4. The method according to claim 1, wherein: The loss function is determined based on a negative value of quantum channel coherent information of the first quantum channel under a coding scheme corresponding to the second quantum state.

5. The method according to claim 4, wherein: The loss function C(θ)=-2 k *L*I(N,ψ(θ)); wherein θ is the target parameter, L is the circuit depth of the parameterized quantum circuit, k is the number of quantum bits of the parameterized quantum circuit, and I(N,ψ(θ)) is the quantum channel coherence information of the first quantum channel N under the coding scheme corresponding to the second quantum state ψ(θ).

6. The method according to claim 1, wherein: The quantum channel coherent information of the first quantum channel under the coding scheme corresponding to the second quantum state is the quantum relative entropy of a third quantum state and a fourth quantum state, the third quantum state is obtained based on the tensor product operation of the identity mapping of the input state of the first quantum channel on the first quantum system and the target output state, the fourth quantum state is obtained by mapping the target output state on the first quantum system to the unit matrix, the target output state is the output state of the first quantum channel under the coding scheme corresponding to the second quantum state, the input state of the first quantum channel includes the first quantum system and the second quantum system, and the first quantum channel is a quantum channel on the second quantum system.

7. The method according to claim 1, wherein: The second structural information of the parameterized quantum circuit is obtained by: Based on the first structural information of the first quantum channel, the parameterized quantum circuit is constructed to obtain the second structural information.

8. The method according to claim 1, after determining the first target coding scheme of the first quantum channel, further comprising: If the information transmission capacity of the first quantum channel under the first target coding scheme does not meet a preset condition, adjusting the structure of the parameterized quantum circuit; Searching for a coding scheme for the first quantum channel in a search space corresponding to the parameterized quantum circuit after structural adjustment, so as to output a second target coding scheme that enables the information transmission capability of the first quantum channel to meet the preset condition; Among them, if the quantum channel coherence information of the first quantum channel under the first target coding scheme is less than a preset threshold, and / or the information transmission efficiency of the first quantum channel under the first target coding scheme is less than or equal to the information transmission efficiency of the fourth quantum channel, it is determined that the information transmission capacity of the first quantum channel under the first target coding scheme does not meet the preset conditions, and the first quantum channel is formed by connecting the fourth quantum channels in parallel.

9. The method according to claim 1, wherein: The parameterized quantum circuit includes any of the following circuit structures: A first circuit structure, wherein the first circuit structure comprises a layer of single-qubit rotation gates and a layer of fully entangled layers composed of CNOT gates according to the time evolution direction of the quantum state; A second circuit structure, wherein the second circuit structure comprises, according to the time evolution direction of the quantum state, a layer of y-axis single-qubit rotation gate, a layer of linear entanglement layer composed of CNOT gates, a layer of z-axis single-qubit rotation gate and a layer of linear entanglement layer; A third circuit structure, wherein the third circuit structure comprises a layer of y-axis single quantum bit rotation gate and a layer of full entanglement layer according to the time evolution direction of the quantum state; A fourth circuit structure, wherein the fourth circuit structure includes three first blocks consisting of two quantum bits, wherein the first block includes a block consisting of four single-qubit rotation gates and a CNOT gate entangled between the four single-qubit rotation gates, and the first block in the later direction of the quantum state time evolution respectively shares a single-qubit rotation gate with the two first blocks in the front; A fifth circuit structure, the fifth circuit structure includes three second blocks consisting of two quantum bits, the second blocks include a block consisting of four y-axis single-qubit rotation gates and a CNOT gate entangled between the four y-axis single-qubit rotation gates, and the second blocks at the rear in the direction of quantum state time evolution share a y-axis single-qubit rotation gate with the two preceding second blocks respectively.

10. The method according to claim 1, wherein: The iterative updating of the target parameters of the parameterized quantum circuit based on the value of the loss function comprises: Based on the value of the loss function, the target parameters of the parameterized quantum circuit are iteratively updated using a non-gradient dependent optimization method.

11. A quantum channel coding search device, comprising: an acquisition module, configured to acquire target information, wherein the target information includes: first structural information of a first quantum channel, second structural information and target parameters of a parameterized quantum circuit, and a first quantum state characterizing a coding scheme of the first quantum channel; the first structural information includes a channel type and a channel parameter of the first quantum channel, the second structural information is used to indicate a structure of the parameterized quantum circuit, and the target parameters are parameters of a quantum gate of the parameterized quantum circuit; a transformation module, configured to perform a unitary transformation of the parameterized quantum circuit on the first quantum state to obtain a second quantum state representing the coding scheme of the first quantum channel; the unitary transformation is constructed based on the second structural information and a target parameter; A first determining module is used to determine a value of a loss function of the parameterized quantum circuit based on the first structural information and the second quantum state, wherein the loss function is inversely proportional to quantum channel coherence information of the first quantum channel under a coding scheme corresponding to the second quantum state; An iterative updating module, configured to iteratively update target parameters of the parameterized quantum circuit based on the value of the loss function; The second determination module is used to determine a first target coding scheme for the first quantum channel when the iterative update of the target parameter is completed, and the quantum state representing the first target coding scheme is a quantum state obtained by applying a unitary transformation of a parameterized quantum circuit under the target parameter to the first quantum state.

12. The device according to claim 11, wherein The first quantum channel is a quantum channel in which n second quantum channels are transmitted in parallel, and the information transmission efficiency of the first quantum channel under the first target coding scheme is greater than the information transmission efficiency of the second quantum channel transmitted n times, where n is a positive integer greater than 1.

13. The device according to claim 11, wherein: The number of the first quantum channels includes m, each of the first quantum channels is formed by connecting third quantum channels of the same type in parallel, different first quantum channels correspond to different third quantum channels, and m is a positive integer greater than 1. The device further includes: A screening module is used to screen out a target quantum channel from the m first quantum channels based on a first target coding scheme of each first quantum channel, wherein the information transmission efficiency of the target quantum channel under the first target coding scheme is greater than the information transmission efficiency of a third quantum channel corresponding to the target quantum channel transmitted k times, where k is the number of third quantum channels connected in parallel.

14. The device according to claim 11, wherein: The loss function is determined based on a negative value of quantum channel coherent information of the first quantum channel under a coding scheme corresponding to the second quantum state.

15. The device according to claim 14, wherein: The loss function C(θ)=-2 k *L*I(N,ψ(θ)); wherein θ is the target parameter, L is the circuit depth of the parameterized quantum circuit, k is the number of quantum bits of the parameterized quantum circuit, and I(N,ψ(θ)) is the quantum channel coherence information of the first quantum channel N under the coding scheme corresponding to the second quantum state ψ(θ).

16. The device according to claim 11, wherein The quantum channel coherent information of the first quantum channel under the coding scheme corresponding to the second quantum state is the quantum relative entropy of a third quantum state and a fourth quantum state, the third quantum state is obtained based on the tensor product operation of the identity mapping of the input state of the first quantum channel on the first quantum system and the target output state, the fourth quantum state is obtained by mapping the target output state on the first quantum system to the unit matrix, the target output state is the output state of the first quantum channel under the coding scheme corresponding to the second quantum state, the input state of the first quantum channel includes the first quantum system and the second quantum system, and the first quantum channel is a quantum channel on the second quantum system.

17. The device according to claim 11, wherein: The second structural information of the parameterized quantum circuit is obtained by: Based on the first structural information of the first quantum channel, the parameterized quantum circuit is constructed to obtain the second structural information.

18. The apparatus according to claim 11, further comprising: an adjustment module, configured to adjust the structure of the parameterized quantum circuit if the information transmission capability of the first quantum channel under the first target coding scheme does not meet a preset condition; An output module, configured to search for a coding scheme of the first quantum channel in a search space corresponding to the parameterized quantum circuit after structural adjustment, so as to output a second target coding scheme that enables the information transmission capacity of the first quantum channel to meet the preset condition; Among them, if the quantum channel coherence information of the first quantum channel under the first target coding scheme is less than a preset threshold, and / or the information transmission efficiency of the first quantum channel under the first target coding scheme is less than or equal to the information transmission efficiency of the fourth quantum channel, it is determined that the information transmission capacity of the first quantum channel under the first target coding scheme does not meet the preset conditions, and the first quantum channel is formed by connecting the fourth quantum channels in parallel.

19. The device according to claim 11, wherein: The parameterized quantum circuit includes any of the following circuit structures: A first circuit structure, wherein the first circuit structure comprises a layer of single-qubit rotation gates and a layer of fully entangled layers composed of CNOT gates according to the time evolution direction of the quantum state; A second circuit structure, wherein the second circuit structure comprises, according to the time evolution direction of the quantum state, a layer of y-axis single-qubit rotation gate, a layer of linear entanglement layer composed of CNOT gates, a layer of z-axis single-qubit rotation gate and a layer of linear entanglement layer; A third circuit structure, wherein the third circuit structure comprises a layer of y-axis single quantum bit rotation gate and a layer of full entanglement layer according to the time evolution direction of the quantum state; A fourth circuit structure, wherein the fourth circuit structure includes three first blocks consisting of two quantum bits, wherein the first block includes a block consisting of four single-qubit rotation gates and a CNOT gate entangled between the four single-qubit rotation gates, and the first block in the later direction of the quantum state time evolution respectively shares a single-qubit rotation gate with the two first blocks in the front; A fifth circuit structure, the fifth circuit structure includes three second blocks consisting of two quantum bits, the second blocks include a block consisting of four y-axis single-qubit rotation gates and a CNOT gate entangled between the four y-axis single-qubit rotation gates, and the second blocks at the rear in the direction of quantum state time evolution share a y-axis single-qubit rotation gate with the two preceding second blocks respectively.

20. The device according to claim 11, wherein The iterative update module is specifically used for: Based on the value of the loss function, the target parameters of the parameterized quantum circuit are iteratively updated using a non-gradient dependent optimization method.

21. An electronic device comprising: at least one processor; as well as a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 10.

22. A non-transitory computer-readable storage medium storing computer instructions, wherein: The computer instructions are used to cause the computer to execute the method according to any one of claims 1-10.

23. A computer program product comprising a computer program, which, when executed by a processor, implements the method according to any one of claims 1 to 10.

Images